High-entropy carbonitride reinforced cermet material, preparation method and application thereof

Abstract

This invention discloses a high-entropy carbonitride-reinforced cermet material, its preparation method, and its applications, belonging to the field of hard materials technology. The material consists of 85%–95% cermet matrix and 5%–15% high-entropy carbonitride reinforcing phase. The cermet matrix uses TiCN as the hard phase and Ni-Mo alloy as the binder phase; the high-entropy carbonitride reinforcing phase consists of (Ti, Zr, Ta, Nb, Hf)CN solid solution nanoparticles, forming a dual distribution morphology of "grain boundary pinning + intragranular dispersion" within the matrix. This material possesses high hardness, high toughness, good red hardness, and strong oxidation resistance, making it suitable for manufacturing high-performance cutting tools.

Description

Technical Field

[0001] This invention belongs to the field of hard materials technology, and particularly relates to a high-entropy carbonitride reinforced cermet material, its preparation method and application. Background Technology

[0002] Titanium carbonitride (TiCN)-based cermets are advanced materials composed of a ceramic hard phase (TiCN) and a metal binder phase (such as Ni or Mo) through powder metallurgy. Due to their high hardness, high wear resistance, low coefficient of friction, and good chemical stability, they have become important tool materials for precision machining and ultra-precision machining of steel and cast iron parts.

[0003] However, traditional TiCN-based cermets have inherent performance limitations that restrict their application range: First, they have insufficient fracture toughness, making them prone to chipping during intermittent cutting or rough machining; second, they have limited red hardness, as the metal binder phase softens easily when the cutting temperature exceeds 800-900℃, leading to a sharp decrease in tool hardness and an inability to maintain effective cutting capability; third, their high-temperature oxidation resistance needs improvement, as a loose oxide layer easily forms on the surface above 1000℃, failing to effectively prevent oxygen from diffusing inward, resulting in continuous oxidation and corrosion of the matrix and further accelerating tool failure; fourth, it is difficult to improve hardness and toughness simultaneously. While adding conventional second phases such as tungsten carbide (WC) and tantalum carbide (TaC) can improve hardness, it is often accompanied by a significant decrease in toughness, making synergistic optimization difficult to achieve.

[0004] Therefore, there is an urgent need to provide a metal-ceramic material with a novel reinforcement mechanism that can significantly improve toughness, red hardness, and oxidation resistance while maintaining high hardness, achieving synergistic breakthroughs in multiple key properties. Summary of the Invention

[0005] The purpose of this invention is to provide a high-entropy carbonitride-reinforced cermet material, its preparation method and application, to solve the above-mentioned technical problems and improve the hardness, toughness, red hardness and oxidation resistance of cermet materials.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, a high-entropy carbonitride-reinforced cermet material is provided, the composition of which, by volume fraction, is as follows: Metal-ceramic matrix: 85%~95%; High-entropy carbonitride reinforced phase: 5%~15%; The metal-ceramic matrix comprises a hard phase and a binder phase. The hard phase is titanium carbonitride (TiCN), and the binder phase is an alloy composed of nickel (Ni) and molybdenum (Mo), wherein Ni accounts for 70% to 95% of the total mass of the binder phase, and Mo accounts for 5% to 30% of the total mass of the binder phase. The high-entropy carbonitride reinforcing phase is a (Ti,Zr,Ta,Nb,Hf)CN solid solution nanoparticle with a face-centered cubic crystal structure, and the high-entropy carbonitride reinforcing phase forms a dual distribution morphology of "grain boundary pinning + intragranular dispersion" in the metal ceramic matrix.

[0007] Optionally, in the high-entropy carbonitride reinforced phase, the molar ratio of the five metal elements Ti, Zr, Ta, Nb, and Hf is (0.8-1.2):(0.8-1.2):(0.8-1.2):(0.8-1.2):(0.8-1.2).

[0008] Optionally, the high-entropy carbonitride reinforced phase nanoparticles have an average particle size of 50~500nm, wherein particles with a particle size of 50~200nm account for ≥60%, and there are no aggregates with a size exceeding 1μm.

[0009] Optionally, the C / N atomic ratio of the TiCN hard phase is 0.8~1.2, and the particle size of the TiCN particles is 0.5~2.0μm, wherein the proportion of particles with a particle size of 0.8~1.5μm is ≥70%.

[0010] Secondly, a method for preparing the above-mentioned high-entropy carbonitride-reinforced metal-ceramic material is provided, comprising the following steps: (1) Raw material preparation: Weigh TiCN powder, Ni powder, Mo powder, and high-entropy carbonitride precursor according to the volume fraction ratio of 85%~95% for the metal ceramic matrix and 5%~15% for the high-entropy carbonitride reinforcing phase; the high-entropy carbonitride precursor is a pre-synthesized (Ti,Zr,Ta,Nb,Hf)CN high-entropy alloy powder, or contains powder, A mixture of powder, Ta elemental powder, Nb elemental powder, Hf elemental powder and a carbon-nitrogen source, wherein the carbon-nitrogen source is one or two of graphite powder and urea, and the C / N atomic ratio in the carbon-nitrogen source is 1:0.8~1.2; (2) Ball milling: Place all the raw material powders from step (1) into a ball mill, add grinding balls, and ball mill under an inert atmosphere to obtain mixed powder; (3) Drying and sieving: The ball-milled mixed powder is vacuum dried and then sieved to obtain powder raw material; (4) Mold loading: The sieved powder raw material is loaded into the mold and placed in the sintering chamber of the vibrating sintering equipment, and a vacuum is drawn; (5) Vibration sintering: The powder raw material loaded into the mold is subjected to segmented heating and sintering, including: Degassing stage: Heat to 800-900℃ at a rate of 10-15℃ / min and hold for 10-15 minutes; Sintering densification stage: The temperature is increased from the holding temperature of the degassing stage to 1350℃~1500℃ at a rate of 5~8℃ / min. During the heating process, the high-frequency vibration device is turned on. The vibration frequency during the heating stage is 50~100 Hz and the amplitude is 0.1~0.2 μm. After reaching the holding temperature, an axial pressure of 30~50 MPa is applied, and the vibration parameters are switched to the holding stage vibration frequency of 150~200 Hz and the amplitude of 0.3~0.5 μm. The holding time is 5~15 minutes. Cooling phase: Stop heating, maintain pressure and vibration until the temperature drops below 500°C, then stop pressurizing and vibration, and allow to cool naturally to room temperature; (6) Subsequent processing: Demold the sintered blank and perform mechanical processing to remove the surface oxide layer and excess parts to obtain the metal ceramic material.

[0011] Optionally, in step (2), the ball milling is carried out using a high-energy ball mill with a ball-to-material ratio of 10:1 to 20:1, a rotation speed of 250 to 350 rpm, and a ball milling time of 15 to 25 hours; after ball milling, a mixed powder with a particle size distribution D50 of 0.3 to 1.0 μm is obtained.

[0012] Optionally, when step (1) uses powder, When powder, Ta elemental powder, Nb elemental powder, Hf elemental powder and carbon and nitrogen source are used as high-entropy carbon and nitrogen precursors, the total amount of carbon and nitrogen source added is 5% to 10% in excess of the theoretical amount of carbon and nitrogen required for the complete reaction of each metal element to generate (Ti,Zr,Ta,Nb,Hf)CN.

[0013] Thirdly, a high-entropy carbonitride-reinforced cermet material prepared by the above-described preparation method is provided.

[0014] Fourthly, a cutting tool is provided, wherein the working part of the cutting tool tip or the entire cutting tool is made of the aforementioned high-entropy carbonitride-reinforced cermet material.

[0015] Fifthly, a coated cutting tool is provided, comprising a tool substrate and a multilayer composite coating, wherein the tool substrate is made of the aforementioned high-entropy carbonitride-reinforced cermet material; the composite coating consists of a transition layer, a bonding layer, and an outermost layer from the inside out; the outermost layer is a (Ti,Zr,Ta,Nb,Hf)CN high-entropy carbonitride coating with a thickness of 2~5μm.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a high-entropy carbonitride-reinforced cermet material. By introducing a high-entropy carbonitride reinforcing phase and optimizing the composition of the cermet matrix, and utilizing its dual distribution morphology of "grain boundary pinning + intragranular dispersion", it successfully overcomes the defects of traditional TiCN-based cermets, such as "difficulty in balancing hardness and toughness" and insufficient high-temperature performance. It can significantly improve toughness, red hardness and oxidation resistance while maintaining high hardness. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the microstructure of the high-entropy carbonitride-reinforced cermet material of the present invention.

[0018] Figure 2 This is a bar chart comparing the room temperature hardness of the material in Example 1 of the present invention with that of Comparative Example 1 (traditional TiCN-based cermet).

[0019] Figure 3 This is a comparison chart of the hardness retention rate at 1100℃ between the material in Example 1 of the present invention and Comparative Example 1.

[0020] Figure 4 The image shows the XRD pattern of the material in Example 1 of this invention.

[0021] Figure 5 This is a scanning electron microscope (SEM) image of the material in Embodiment 1 of the present invention. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention without departing from the spirit and scope of the present invention should be covered within the protection scope of the present invention. In the following embodiments, process equipment or devices not specifically specified are all conventional equipment or devices in the art. Unless otherwise specified, the raw materials used in the embodiments of the present invention are commercially available; unless otherwise specified, the technical means used in the embodiments of the present invention are all conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the technical field.

[0023] refer to Figure 1 This application provides a high-entropy carbonitride-reinforced cermet material, the composition of which, by volume fraction, is as follows: Metal-ceramic matrix: 85%~95%; High-entropy carbonitride reinforced phase: 5%~15%; The cermet matrix comprises a hard phase and a binder phase. The hard phase is titanium carbonitride (TiCN), and the binder phase is an alloy composed of nickel (Ni) and molybdenum (Mo), wherein Ni accounts for 70% to 95% of the total mass of the binder phase, and Mo accounts for 5% to 30% of the total mass of the binder phase. The high-entropy carbonitride reinforcing phase is a (Ti,Zr,Ta,Nb,Hf)CN solid solution nanoparticle with a face-centered cubic crystal structure, and the high-entropy carbonitride reinforcing phase forms a dual distribution morphology of "grain boundary pinning + intragranular dispersion" in the metal ceramic matrix.

[0024] The Ni-Mo alloy acts as a binder phase, forming a liquid phase during sintering. This liquid phase wets and binds the TiCN hard phase particles and the high-entropy carbonitride reinforcing phase particles, improving the material's density and toughness. Ni accounts for 70%–95% of the total mass of the binder phase, providing excellent wettability and toughness; Mo accounts for 5%–30%, improving the high-temperature strength of the binder phase, promoting interfacial bonding between TiCN and the reinforcing phase, and inhibiting the formation of brittle phases.

[0025] The high-entropy carbonitride reinforcing phase consists of (Ti,Zr,Ta,Nb,Hf)CN solid solution nanoparticles with a face-centered cubic (FCC) crystal structure. The five refractory metal elements selected—titanium (Ti), zirconium (Zr), tantalum (Ta), niobium (Nb), and hafnium (Hf)—are all strong carbonitride forming elements with similar atomic radii (the maximum difference is about 9.6%), all have an FCC crystal structure (NaCl type), and similar chemical properties, making it easy to form a single, stable substitutional solid solution. Their carbonitrides themselves all have high hardness, high melting point, and excellent thermal stability. After forming high-entropy carbonitrides, their performance is further improved through the high-entropy effect and lattice distortion effect.

[0026] The core mechanism for improving the material performance of this invention lies in the "intrinsic effect of the high-entropy reinforcing phase," and the strengthening and toughening mechanism of the high-entropy reinforcing phase is as follows: (1) Fine grain strengthening: High entropy carbonitride nanoparticles are uniformly dispersed at the TiCN grain boundaries, pinning the grain boundaries and inhibiting the growth of TiCN matrix grains during sintering. According to the Hall-Page formula, the finer the grains, the higher the material strength and hardness. (2) Dispersion strengthening (second phase strengthening): High entropy carbonitrides themselves have ultra-high hardness (≥30GPa). As hard particles, they are uniformly distributed in the matrix, effectively bearing external forces, hindering dislocation movement and plastic deformation, and significantly improving the macroscopic hardness and wear resistance of the material. (3) Lattice distortion strengthening: The atomic radii of the five metal elements in high-entropy carbonitrides are different, which leads to severe lattice distortion, generates a strong internal stress field, hinders dislocation slip and proliferation, and further improves the strength and hardness of the material; (4) Crack deflection and bridging toughening: When microcracks are generated in the material under external force, the crack propagation encounters high-entropy carbonitride particles. Due to the two-phase interface effect, the crack deflects, bypasses, or is "pinned" by the particles, which consumes a large amount of fracture energy, prevents the crack from propagating rapidly, and improves fracture toughness.

[0027] In some implementations, the lattice constant of the crystal structure is between 4.35 Å and 4.45 Å.

[0028] In some embodiments, the molar ratio of the five metal elements Ti, Zr, Ta, Nb, and Hf in the high-entropy carbonitride reinforced phase is (0.8-1.2):(0.8-1.2):(0.8-1.2):(0.8-1.2):(0.8-1.2).

[0029] In some implementations, the molar ratio of the five metal elements Ti, Zr, Ta, Nb, and Hf is 1:1:1:1:1 to ensure that the high entropy effect is fully utilized.

[0030] In some embodiments, the high-entropy carbonitride reinforcing phase nanoparticles have an average particle size of 50~500nm, of which particles with a particle size of 50~200nm account for ≥60%, and there are no aggregates with a size exceeding 1μm. The reinforcing phase forms a dual distribution morphology of "grain boundary pinning + intragranular dispersion" in the matrix, which can significantly improve hardness through fine grain strengthening and dispersion strengthening, and improve toughness through crack deflection, bridging and other mechanisms.

[0031] In some embodiments, the material further comprises 0.5% to 5% by volume an additive, the additive being selected from vitamin C, etc. One or more of VC and TaC can further refine the grain size and improve the material's wear resistance and high-temperature stability. Among them, VC and... The compound addition ratio is 1:0.5~2. Through multi-component compound addition, the performance can be precisely controlled. The total mass of the additives does not exceed 5% of the total volume of the material to avoid excessive addition affecting the toughness of the material.

[0032] In some embodiments, the C / N atomic ratio of the TiCN hard phase is 0.8 to 1.2, and the particle size of the TiCN particles is 0.5 to 2.0 μm, with particles having a diameter of 0.8 to 1.5 μm accounting for ≥70%, ensuring that the coefficient of variation of the matrix grain size uniformity is ≤15%. As a hard phase, TiCN provides the material's basic hardness and wear resistance. Its C / N atomic ratio is designed to be 0.8 to 1.2, within which TiCN exhibits a stable crystal structure and excellent mechanical properties. The particle size of the TiCN particles is limited to 0.5 to 2.0 μm, with particles having a diameter of 0.8 to 1.5 μm accounting for ≥70%, ensuring the uniformity of the matrix grain size and providing a basis for the uniform distribution of the reinforcing phase.

[0033] This application also provides a method for preparing the above-mentioned high-entropy carbonitride reinforced metal-ceramic material, comprising the following steps: S1. Raw material preparation: Weigh TiCN powder, Ni powder, Mo powder, and high-entropy carbonitride precursor according to the volume fraction ratio of 85%~95% metal-ceramic matrix and 5%~15% high-entropy carbonitride reinforcing phase; the high-entropy carbonitride precursor is a pre-synthesized (Ti,Zr,Ta,Nb,Hf)CN high-entropy alloy powder, or powder containing... powder, A mixture of powders, elemental Ta powder, elemental Nb powder, elemental Hf powder, and a carbon-nitrogen source, wherein the carbon-nitrogen source is one or both of graphite powder and urea, and the C / N atomic ratio in the carbon-nitrogen source is 1:0.8~1.2; (Selection) The reason for using non-Ti elemental powder is that... During ball milling and sintering, decomposition occurs. It can effectively remove the oxide film on the powder surface and activate the powder at the same time; the carbon-nitrogen molar ratio of the carbon-nitrogen source is controlled at 1:0.8~1.2 to ensure that the generated high-entropy carbonitride composition is uniform.

[0034] In some implementations, when using powder, When elemental powders (Ta, Nb, and Hf) are used as precursors for high-entropy carbonitrides, the total amount of carbonitrides added is 5%–10% in excess of the theoretical amount of carbon and nitrogen required for the complete reaction of each metal element to form (Ti, Zr, Ta, Nb, Hf)CN. This is to compensate for the volatilization loss of carbon and nitrogen during the high-temperature sintering stage and ensure that the C / N atomic ratio in the high-entropy carbonitrides generated after the in-situ reaction remains within the range of 1:0.8–1.2.

[0035] S2. Ball milling: Place all the raw material powders from step (1) into a ball mill, add grinding balls, and ball mill under an inert atmosphere to obtain mixed powder. Ball mill under an argon inert atmosphere to prevent powder oxidation.

[0036] In some embodiments, ball milling is carried out using a high-energy ball mill with a ball-to-material ratio of 10:1 to 20:1, a rotation speed of 250 to 350 rpm, and a milling time of 15 to 25 hours; after ball milling, a mixed powder with a particle size distribution D50 of 0.3 to 1.0 μm is obtained.

[0037] In some embodiments, the grinding balls are made of cemented carbide, with a diameter of 8-12 mm. The ratio of 8 mm, 10 mm, and 12 mm grinding balls is 1:2:1 to achieve efficient refining and mixing of powders of different sizes. Through mechanical alloying, the powder components are thoroughly and uniformly mixed, while simultaneously achieving particle refinement and lattice distortion.

[0038] S3. Drying and Sieving: The ball-milled mixed powder is vacuum dried and then sieved to obtain powder raw material. The ball-milled mixed powder contains a certain amount of moisture and residual gas. The drying process removes moisture and gas to avoid defects such as pores during sintering. The dried powder is passed through a 100-200 mesh standard sieve. Ultrasonic-assisted dispersion is used during the sieving process to remove agglomerates and any impurities that may be introduced, ensuring the uniformity and flowability of the powder.

[0039] In some embodiments, the ball-milled powder is vacuum dried in stages at 80~120°C for 4~8 hours (e.g., 80°C for 2 hours, 100°C for 2 hours, and 120°C for 2 hours). After drying, it is passed through a 100~200 mesh sieve and then ultrasonically dispersed (300W power, 10 minutes) to remove agglomerates and impurities, thereby obtaining a uniform and fine powder raw material.

[0040] S4. Mold loading: The sieved powder raw material is loaded into the mold and placed in the sintering chamber of the vibrating sintering equipment. Vacuum is drawn to remove residual oxygen in the chamber.

[0041] In some embodiments, the sieved powder is loaded into a graphite mold with an inner wall coated with graphite emulsion (0.1~0.3 mm thick) to reduce the adhesion between the powder and the mold during sintering and facilitate subsequent demolding.

[0042] S5. Vibration sintering: The powder raw material loaded into the mold is sintered by segmented heating, including: Degassing stage: Heat to 800-900℃ at a rate of 10-15℃ / min and hold for 10-15 minutes; monitor the partial pressure of gas in the chamber in real time during the degassing process, and proceed to the next stage when the partial pressure is ≤1×10-3Pa.

[0043] Sintering densification stage: The temperature is increased to 1350℃~1500℃ at a rate of 5~8℃ / min. During the heating process, the high-frequency vibration device is turned on. The vibration frequency during the heating stage is 50~200 Hz and the amplitude is 0.1~0.2 μm. After reaching the holding temperature, an axial pressure of 30~50 MPa is applied, and the vibration parameters are switched to the holding stage vibration frequency of 150~200 Hz and the amplitude of 0.3~0.5 μm. The holding time is 5~15 minutes. This temperature is lower than the traditional sintering temperature (1520~1600℃), which can effectively inhibit grain growth and harmful interfacial reactions. The applied axial pressure promotes the contact and deformation of powder particles, accelerating densification. The vibration energy promotes particle sliding and rearrangement, breaks the oxide film, strengthens atomic diffusion, and achieves uniform dispersion of the reinforcing phase and tight bonding at the interface. Densification is completed after holding for 5~15 minutes.

[0044] Cooling phase: Stop heating, maintain pressure and vibration until the temperature drops below 500°C, then stop pressurizing and vibration, and allow to cool naturally to room temperature.

[0045] In some implementations, the pressure applied during oscillatory sintering is applied in a stepped manner.

[0046] In some implementations, the cooling rate during the cooling phase is controlled at 8~12℃ / min to reduce internal thermal stress in the material and avoid microcracks. Then, the pressurization and vibration are stopped, and the material is allowed to cool naturally to room temperature.

[0047] In some implementations, axial sinusoidal vibration is performed when the high-frequency vibration device is activated. The frequency and amplitude fluctuation range during vibration is ≤±5%, ensuring stable energy input during sintering.

[0048] S6. Subsequent processing: Demold the sintered green body and perform machining to remove the surface oxide layer and excess material to obtain the metal ceramic material.

[0049] In some implementations, machining includes wire cutting, grinding, or polishing.

[0050] By adopting a combined process route of "ball milling + oscillating sintering", the synergistic optimization of raw material mixing homogenization, particle refinement, uniform dispersion of reinforcing phase and material densification is achieved.

[0051] The core mechanism for performance improvement in the material preparation method of this invention lies in the "process effect of oscillatory sintering," and the process strengthening mechanism of oscillatory sintering is as follows: (1) Promote densification: High-frequency vibration reduces the critical yield stress of powder particles, promotes particle slippage and rearrangement, reduces interparticle porosity, and improves material density; (2) Strengthening the interface bonding: Vibration energy breaks the oxide film and adsorption layer on the surface of powder particles, promotes direct contact and atomic diffusion between particles, and enables the high-entropy reinforcing phase to form a tight metallurgical bond with the TiCN matrix and Ni-Mo bonding phase, thus avoiding interface debonding; (3) Suppress grain coarsening: The low-temperature and rapid characteristics of oscillatory sintering shorten the grain growth time, and the stress field generated by vibration suppresses abnormal grain growth and maintains the fine grain structure of the material; (4) Improve the dispersion of the reinforcing phase: The shear force and impact force generated during vibration break up the powder agglomerates, so that the high-entropy carbonitride particles are uniformly dispersed in the matrix, giving full play to the reinforcing effect.

[0052] This application also provides a high-entropy carbonitride-reinforced cermet material prepared by the above-described preparation method.

[0053] This application also provides a cutting tool, wherein the working part of the cutting tool tip or the entire cutting tool is made of the above-mentioned high-entropy carbonitride reinforced cermet material.

[0054] In some implementations, the cutting tool includes a lathe tool, a milling cutter, a drill bit, a boring tool, or a reamer.

[0055] In some embodiments, the rake angle of the cutting tool is -10° to 5°, the clearance angle is 0° to 15°, the tool tip radius is 0.2 to 1.2 mm, and the working surface of the tool tip is polished to a Ra≤0.1 μm.

[0056] This application also provides a coated cutting tool, including a tool substrate and a multilayer composite coating. The tool substrate is made of the above-mentioned high-entropy carbonitride-reinforced cermet material. The composite coating consists of a transition layer, a bonding layer and an outermost layer from the inside to the outside. The outermost layer is a (Ti,Zr,Ta,Nb,Hf)CN high-entropy carbonitride coating with a thickness of 2~5μm.

[0057] In some embodiments, the transition layer is TiN or TiCN, with a thickness of 0.5~1μm and a density of ≥99%.

[0058] In some embodiments, the adhesive layer is TiAlN with a thickness of 1~2μm and an Al content of 40%~60% of the total mass of TiAlN.

[0059] In some embodiments, the composite coating is prepared by magnetron sputtering or arc ion plating.

[0060] In some embodiments, the C / N atomic ratio in the outermost (Ti,Zr,Ta,Nb,Hf)CN high-entropy carbonitride coating is 0.5 to 2.0. Example 1

[0061] This embodiment is used to demonstrate the preparation and properties of the high-entropy carbonitride-reinforced cermet material described in this invention.

[0062] 1. Raw material preparation: Weigh the following powders by volume fraction: 67% titanium carbonitride (TiCN) powder (C / N atomic ratio of 1.0, TiCN particle size 1.0μm), 15% nickel (Ni) powder (particle size 3μm), 6% molybdenum (Mo) powder (particle size 2μm), and 2% vanadium carbide (VC) powder (particle size 1.5μm). These constitute the cermet matrix (total volume percentage 90%); pre-synthesized ( CN high-entropy carbonitride powder (particle size 200nm) is used as the reinforcing phase, accounting for 10%. Zinc stearate, accounting for 0.3% of the total mass of raw materials, is added as a dispersant to improve powder dispersibility and reduce agglomeration. The dispersant decomposes and volatilizes during the low-temperature sintering stage and does not remain in the final material.

[0063] 2. High-energy ball milling: The above raw materials and cemented carbide grinding balls (ball-to-material ratio 15:1) are placed in a high-energy planetary ball mill and milled at 300 rpm for 20 hours under an inert atmosphere (such as argon) to obtain a mixed powder with a D50 of 0.6 μm. To ensure the uniform refinement and dispersion of the mixed powder, intermittent ball milling is used to prevent powder overheating and agglomeration, such as stopping the ball mill for 15 minutes every 5 hours.

[0064] 3. Drying and sieving: The ball-milled powder is vacuum dried in stages at 80~120℃ for 6 hours (e.g., 80℃ for 2 hours, 100℃ for 2 hours, and 120℃ for 2 hours). After drying, it is sieved through a 150-mesh sieve and then ultrasonically dispersed (300W power, 10 minutes) to remove agglomerates and impurities, and obtain a uniform and fine powder raw material.

[0065] 4. Mold Loading: The sieved powder is loaded into a graphite mold with graphite emulsion coated on the inner wall, placed into the cavity of the vibrating sintering furnace, and evacuated until... Pa, maintain for 30 minutes to ensure no residual oxygen in the cavity and prevent oxidation of the powder during sintering.

[0066] 5. Vibration sintering: Start the oscillating sintering equipment and perform segmented heating sintering according to the following parameters: Degassing stage: Increase the temperature to 850℃ at a rate of 12℃ / min and hold for 12 minutes.

[0067] Sintering densification stage: The temperature is increased from 850℃ to 1450℃ at a rate of 6℃ / min. During the heating process, the high-frequency vibration device is turned on to perform axial sinusoidal vibration. The vibration frequency during the heating stage is 80 Hz and the amplitude is 0.2 μm. After reaching 1450℃, axial pressure is applied in a stepped pressurization method (30MPa for 2 minutes, 40MPa for 2 minutes, and 50MPa for 8 minutes until the end of the stage). At the same time, the vibration parameters are switched to the holding stage with a vibration frequency of 180 Hz and an amplitude of 0.4 μm for 8 minutes.

[0068] Cooling stage: Stop heating, maintain pressure and vibration, cool to 500℃ at 10℃ / min, then depressurize, stop vibration, and allow to cool naturally to room temperature.

[0069] The oscillating sintering equipment is equipped with a piezoelectric ceramic driven vibration generator that can apply axial sinusoidal vibration to the graphite mold, with the vibration frequency and amplitude continuously adjustable within the range.

[0070] 6. Subsequent processing: The sintered green body is demolded and cut into standard test samples (size: 5mm×5mm×30mm bending strength sample, Φ10mm×5mm hardness test sample) by wire cutting equipment. Then the samples are ground and polished to remove the surface oxide layer and defects. The final sample density is 99.6% and the surface roughness Ra=0.15μm.

[0071] The material properties tested were as follows: density 99.6%, Vickers hardness 34.2 GPa, and fracture toughness 9.1 MPa·m. 1 / 2 The room temperature flexural strength is 1880 MPa, the hardness retention rate at 1100℃ is 93%, the oxidation initiation temperature is 1120℃, and the weight gain per unit area after static oxidation at 1100℃ for 10 hours is 3.2 mg / cm².

[0072] right Figure 5 Image analysis and statistical analysis of the SEM images shown revealed the formation of a dual distribution morphology of high-entropy carbonitride-reinforced phases, characterized by "grain boundary pinning + intragranular dispersion". Example 2

[0073] This embodiment is basically the same as Embodiment 1, except that: the metal ceramic matrix accounts for 85% of the total volume, and the high-entropy carbonitride reinforcing phase accounts for 15%; the densification stage of the oscillating sintering is heated to 1500℃, the vibration parameters of the heating stage are 100 Hz and 0.2 μm, the vibration parameters of the holding stage are 200 Hz and 0.5 μm, and the holding time is 5 minutes.

[0074] The material properties tested were as follows: density 99.1%, Vickers hardness 35.6 GPa, and fracture toughness 8.7 MPa·m. 1 / 2 The room temperature flexural strength is 1850 MPa, the hardness retention rate at 1100℃ is 91%, the oxidation initiation temperature is 1115℃, and the weight gain per unit area after static oxidation at 1100℃ for 10 hours is 3.5 mg / cm².

[0075] Image analysis and statistical analysis of the SEM images showed that the high-entropy carbonitride reinforced phase had a dual distribution morphology consistent with that of Example 1. Example 3

[0076] This embodiment is basically the same as Embodiment 1, except that: the metal ceramic matrix accounts for 95% of the total volume, and the high-entropy carbonitride reinforcing phase accounts for 5%; the densification stage temperature of the oscillation sintering is 1350℃, the vibration parameters of the heating stage are 50 Hz and 0.1 μm, the vibration parameters of the holding stage are 150 Hz and 0.3 μm, and the holding time is 15 minutes.

[0077] The material properties tested were as follows: density 98.8%, Vickers hardness 31.5 GPa, and fracture toughness 9.3 MPa·m. 1 / 2 The room temperature flexural strength is 1900 MPa, the hardness retention rate at 1100℃ is 88%, the oxidation initiation temperature is 1105℃, and the weight gain per unit area after static oxidation at 1100℃ for 10 hours is 3.8 mg / cm².

[0078] Image analysis and statistical analysis of the SEM images showed that the high-entropy carbonitride reinforced phase had a dual distribution morphology consistent with that of Example 1.

[0079] The main performance test results of each embodiment are summarized in Table 1 below.

[0080] Comparative Example 1: TiCN-based cermets without added high-entropy carbonitrides were prepared using a conventional spark plasma sintering (SPS) process. The raw material composition was 77% TiCN, 15% Ni, 6% Mo, and 2% VC (volume fraction), with 0.3% zinc stearate added as a dispersant. The sintering process was as follows: temperature 1550℃, pressure 40 MPa, and vacuum holding for 10 minutes. The remaining steps were the same as in Example 1.

[0081] No observable high-entropy carbonitride-reinforced phase characteristics.

[0082] Comparative Example 2: TiCN-based cermets without the addition of high-entropy carbonitrides were prepared using the same oscillating sintering process as in Example 1. The raw material ratios were the same as in Comparative Example 1.

[0083] No observable high-entropy carbonitride-reinforced phase characteristics.

[0084] The performance test results for Comparative Example 1 and Comparative Example 2 are shown in Table 1.

[0085] Performance Tests and Results

[0086] The following performance tests were performed on the samples obtained in Examples 1-3, Comparative Example 1, and Comparative Example 2:

[0087] (1) Vickers hardness test: HV-120 Vickers hardness tester was used, with a load of 30 kgf and a holding time of 15 seconds. Five points were tested for each sample, and the arithmetic mean was taken as the Vickers hardness value of the sample.

[0088] (2) Fracture toughness test: The indentation method was used. The crack length was measured at the tip of the diagonal of the indentation after the Vickers hardness test. The fracture toughness KIC value was calculated using the Shetty formula. The arithmetic mean of 5 points was taken for each sample. The Shetty formula is as follows:

[0089] In the formula, P—actual load of the indentation, (N); a—half the length of the diagonal of the indentation, (mm); l—length of the indentation crack, (mm).

[0090] (3) Room temperature bending strength test: The three-point bending method was used and the test was conducted on a universal testing machine. The sample size was 5 mm × 5 mm × 30 mm, the span was 20 mm, the loading rate was 0.5 mm / min, and the arithmetic mean of 5 samples were taken for each group of tests.

[0091] (4) High temperature hardness retention rate test: The sample is placed in a muffle furnace and heated to 1100°C in an air atmosphere. After holding at the temperature for 1 hour, it is cooled to room temperature with the furnace. After taking it out, the hardness is measured according to the Vickers hardness test method described above. The hardness retention rate is calculated as (hardness after high temperature treatment / original hardness at room temperature) × 100%.

[0092] (5) Oxidation performance test: The static oxidation method was adopted. The sample with known mass and surface area was placed in a muffle furnace and kept at 1100℃ for 10 hours in air atmosphere. After cooling with the furnace, it was weighed and the weight gain per unit area (mg / cm²) was calculated by (mass after oxidation - mass before oxidation) / sample surface area.

[0093] (6) Oxidation initiation temperature test: Thermogravimetric analyzer was used to heat the sample in air at a heating rate of 10℃ / min. The sample mass change curve with temperature was recorded. The temperature corresponding to the sample mass increase of 0.5% was defined as the oxidation initiation temperature.

[0094] (7) Density test: The actual density of the sample is measured by Archimedes' displacement method and expressed as a percentage of the theoretical density.

[0095] (8) Phase structure analysis: The crystal structure of the sample was analyzed by X-ray diffraction (XRD) to confirm that no impurity phase was generated.

[0096] (9) Microscopic morphology observation: The distribution morphology of the enhancement phase was observed using scanning electron microscopy (SEM).

[0097] The test results are shown in Table 1: Vickers hardness (GPa) 19.5 25.3 34.2 35.6 31.5 <![CDATA[Fracture toughness (MPa·m 1 / 2 )]]> 7.2 8.5 9.1 8.7 9.3 Room temperature flexural strength (MPa) 1550 1780 1880 1850 1900 Hardness retention rate at 1100℃ (%) 62 68.5 93 91 88 Oxidation initiation temperature (°C) 900 950 1120 1115 1105 Weight gain (mg / cm²) after oxidation at 1100℃ for 10 hours 8.6 5.3 3.2 3.5 3.8 Density (%) 96.8 99.5 99.6 99.1 98.8 Enhanced phase distribution morphology — — Grain boundary pinning + intragrain dispersion Grain boundary pinning + intragrain dispersion Grain boundary pinning + intragrain dispersion

[0098] As can be seen from Table 1, compared with the comparative example, the materials prepared in each embodiment of the present invention have achieved significant improvements in room temperature hardness, fracture toughness, flexural strength, high-temperature red hardness, and oxidation resistance. Taking Example 1 as an example, the hardness increased by 75%, and the fracture toughness increased by 26%. The high-temperature performance is particularly outstanding, with a hardness retention rate of 93% at 1100℃, which is much higher than the 62% of traditional materials. The oxidation initiation temperature was increased to 1120℃, and the weight gain after 10 hours of oxidation at 1100℃ was only 3.2 mg / cm², which is 63% lower than that of traditional materials, and the high-temperature oxidation resistance was greatly improved. XRD analysis confirmed that no impurity phases were generated in the sample, and SEM observation verified the distribution morphology of the reinforcing phase as "grain boundary pinning + intragranular dispersion".

[0099] This invention innovatively employs oscillatory sintering technology, achieving uniform dispersion of reinforcing phase particles and rapid densification of the material through the synergistic effect of high-frequency vibration and high-temperature sintering. This effectively solves technical challenges in traditional sintering processes, such as reinforcing phase agglomeration, weak interfacial bonding, and insufficient densification. The prepared cermet material exhibits both high hardness (≥30 GPa) and excellent fracture toughness (≥8 MPa·m). 1 / 2 It possesses excellent red hardness (hardness retention rate ≥85% after holding at 1100℃ for 1 hour) and strong oxidation resistance (oxidation initiation temperature ≥1100℃), making it particularly suitable for manufacturing high-performance cutting tools and providing key material support for efficient, precise, and green machining in modern manufacturing. Example 4 (Application Example)

[0100] This embodiment is used to demonstrate the cutting performance of cutting tools made using the materials of this invention.

[0101] The material prepared in Example 1 was processed into CNMG120408 standard turning inserts (rake angle -5°, clearance angle 0°, tip radius 0.8mm) to obtain uncoated cutting tools. Some inserts were coated with a multi-layer composite coating using magnetron sputtering PVD technology. The coating structure, from the inside out, consisted of: a titanium nitride (TiN) transition layer (0.8μm) + a titanium aluminum nitride (TiAlN) binder layer (1.5μm) + an outermost layer of (Ti,Zr,Ta,Nb,Hf)CN high-entropy carbonitride (3μm, hardness 38 GPa). The adhesion between the coating and the substrate was 65N (scratch test).

[0102] Dry turning tests were conducted on 42CrMo alloy steel (hardness HRC35) with uncoated and coated cutting tools. The dimensions were Φ100mm×200mm, the cutting speed was 320 m / min, the feed rate was 0.15 mm / r, and the depth of cut was 1.0 mm. Commercial high-end TiCN-based cermet inserts (corresponding to material in Example 1) were used as a comparison. Tool life was determined by the tool flank wear VB=0.3mm, and tool life was recorded. The surface roughness Ra of the machined workpiece was measured using a surface roughness meter. The tool wear morphology was observed using an optical microscope, and the wear mechanism was analyzed. The test results are shown in Table 2.

[0103] Table 2. Cutting performance test results: Commercial TiCN-based metal ceramic blades 12 0.85 Adhesive wear + Oxidative wear Uncoated cutting tools of the present invention 68 0.52 slight abrasive wear Coated cutting tools of the present invention 83 0.38 Very slight abrasive wear + self-lubricating oxide film

[0104] Cutting test results show that the tool prepared by this invention has a tool life and surface quality that are far superior to traditional commercial tools when machining difficult-to-machine materials, demonstrating excellent cutting performance and great industrial application value.

[0105] Cutting test results show that, compared with commercial TiCN-based cermet tools, the tool life of the uncoated tool of this invention is increased from 12 minutes to 68 minutes (an improvement of approximately 4.7 times), and the coated tool is further improved to 83 minutes (an improvement of approximately 5.9 times). The surface roughness Ra of the uncoated tool is reduced from 0.85 μm to 0.52 μm (a reduction of approximately 39%), and that of the coated tool is reduced to 0.38 μm (a reduction of approximately 55%). Wear mechanism analysis shows that commercial tools mainly experience adhesive wear and oxidative wear, while the uncoated tool of this invention, due to the high hardness, low coefficient of friction, and excellent oxidation resistance of high-entropy carbonitrides, only experiences slight abrasive wear. Furthermore, the coated tool surface forms a self-lubricating oxide film, further reducing the wear rate. These results fully demonstrate that the high-entropy carbonitride-reinforced titanium carbonitride-based cermet material of this invention has excellent cutting performance and significant industrial application value in high-speed dry cutting of difficult-to-machine materials.

[0106] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-entropy carbonitride-reinforced cermet material, characterized in that, Its composition by volume fraction is as follows: Metal-ceramic matrix: 85%~95%; High-entropy carbonitride reinforced phase: 5%~15%; The metal-ceramic matrix comprises a hard phase and a binder phase. The hard phase is titanium carbonitride (TiCN), and the binder phase is an alloy composed of nickel (Ni) and molybdenum (Mo), wherein Ni accounts for 70% to 95% of the total mass of the binder phase, and Mo accounts for 5% to 30% of the total mass of the binder phase. The high-entropy carbonitride reinforcing phase is a (Ti,Zr,Ta,Nb,Hf)CN solid solution nanoparticle with a face-centered cubic crystal structure, and the high-entropy carbonitride reinforcing phase forms a dual distribution morphology of "grain boundary pinning + intragranular dispersion" in the metal ceramic matrix.

2. The high-entropy carbonitride-reinforced cermet material according to claim 1, characterized in that, In the high-entropy carbonitride reinforced phase, the molar ratio of the five metal elements Ti, Zr, Ta, Nb, and Hf is (0.8-1.2):(0.8-1.2):(0.8-1.2):(0.8-1.2):(0.8-1.2).

3. The high-entropy carbonitride-reinforced cermet material according to claim 1, characterized in that, The high-entropy carbonitride reinforced phase nanoparticles have an average particle size of 50~500nm, of which particles with a particle size of 50~200nm account for ≥60%, and there are no aggregates with a size exceeding 1μm.

4. The high-entropy carbonitride-reinforced cermet material according to claim 1, characterized in that, The C / N atomic ratio of the TiCN hard phase is 0.8~1.2, and the particle size of the TiCN particles is 0.5~2.0μm, of which particles with a particle size of 0.8~1.5μm account for ≥70%.

5. A method for preparing the high-entropy carbonitride-reinforced cermet material according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Raw material preparation: Weigh TiCN powder, Ni powder, Mo powder, and high-entropy carbonitride precursor according to the volume fraction ratio of 85%~95% for the metal ceramic matrix and 5%~15% for the high-entropy carbonitride reinforcing phase; the high-entropy carbonitride precursor is a pre-synthesized (Ti,Zr,Ta,Nb,Hf)CN high-entropy alloy powder, or contains powder, A mixture of powder, Ta elemental powder, Nb elemental powder, Hf elemental powder and a carbon-nitrogen source, wherein the carbon-nitrogen source is one or two of graphite powder and urea, and the C / N atomic ratio in the carbon-nitrogen source is 1:0.8~1.2; (2) Ball milling: Place all the raw material powders from step (1) into a ball mill, add grinding balls, and ball mill under an inert atmosphere to obtain mixed powder; (3) Drying and sieving: The ball-milled mixed powder is vacuum dried and then sieved to obtain powder raw material; (4) Mold loading: The sieved powder raw material is loaded into the mold and placed in the sintering chamber of the vibrating sintering equipment, and a vacuum is drawn; (5) Vibration sintering: The powder raw material loaded into the mold is subjected to segmented heating and sintering, including: Degassing stage: Heat to 800-900℃ at a rate of 10-15℃ / min and hold for 10-15 minutes; Sintering densification stage: The temperature is increased from the holding temperature of the degassing stage to 1350℃~1500℃ at a rate of 5~8℃ / min. During the heating process, the high-frequency vibration device is turned on. The vibration frequency during the heating stage is 50~100 Hz and the amplitude is 0.1~0.2 μm. After reaching the holding temperature, an axial pressure of 30~50 MPa is applied, and the vibration parameters are switched to the holding stage vibration frequency of 150~200 Hz and the amplitude of 0.3~0.5 μm. The holding time is 5~15 minutes. Cooling phase: Stop heating, maintain pressure and vibration until the temperature drops below 500°C, then stop pressurizing and vibration, and allow to cool naturally to room temperature; (6) Subsequent processing: Demold the sintered blank and perform mechanical processing to remove the surface oxide layer and excess parts to obtain the metal ceramic material.

6. The preparation method according to claim 5, characterized in that, In step (2), the ball milling is carried out using a high-energy ball mill with a ball-to-material ratio of 10:1 to 20:1, a rotation speed of 250 to 350 rpm, and a milling time of 15 to 25 hours; after milling, a mixed powder with a particle size distribution D50 of 0.3 to 1.0 μm is obtained.

7. The preparation method according to claim 5, characterized in that, When step (1) adopts powder, When powder, Ta elemental powder, Nb elemental powder, Hf elemental powder and carbon and nitrogen source are used as high-entropy carbon and nitrogen precursors, the total amount of carbon and nitrogen source added is 5% to 10% in excess of the theoretical amount of carbon and nitrogen required for the complete reaction of each metal element to generate (Ti,Zr,Ta,Nb,Hf)CN.

8. A high-entropy carbonitride-reinforced cermet material prepared by the preparation method according to any one of claims 5-7.

9. A cutting tool, characterized in that, The cutting tool's tip working portion or the entire tool is made of the high-entropy carbonitride-reinforced cermet material as described in any one of claims 1-4 or 8.

10. A coated cutting tool, characterized in that, The tool includes a tool substrate and a multilayer composite coating. The tool substrate is made of the high-entropy carbonitride-reinforced cermet material as described in any one of claims 1-4 or 8. The composite coating consists of a transition layer, a bonding layer, and an outermost layer from the inside out. The outermost layer is a (Ti,Zr,Ta,Nb,Hf)CN high-entropy carbonitride coating with a thickness of 2-5 μm.

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